Users employ various methods to access network resources such as the Internet. Indeed, some users have constructed small-scale network environments at home. Such users often desire to access the home-based resources from outside, freely and safely. They may always keep their computers at home connected to the Internet, and may have fixed public IP addresses. In such cases, methods such as ADSL, Ethernet, GPRS, PPP, and so forth, can be used. A common shortcoming of these methods is that the so-connected computers are liable to being attacked by hackers, since they are always exposed to the Internet environment.
In order to prevent the occurrence of attacks by hackers, users may employ technology that combines Virtual Private Networks (VPN) and firewalls. With such a combination, computer resources are located behind firewalls and have no public IP addresses, and thus the danger of being successfully attacked by hackers is greatly reduced. But such a configuration needs a specialized network manager that must itself be vigorously defended against hackers, thus increasing total cost.
Consequently, there is a need to ensure that the home-based computer resources can be accessed when needed, and that safety from attack by hackers is provided, all the while minimizing total costs.